1. Field of the Invention
The invention generally relates to storing and retrieving data on a disc drive.
2. Background of the Related Art
Disc drives are capable of storing large amounts of digital data in a relatively small area. Disc drives store information on one or more recording media. The recording media conventionally takes the form of a circular storage disc, e.g., media, having a plurality of recording tracks. Conventional disc drives include one or more vertically aligned storage discs, each with at least one magnetic head for reading or writing information to the media. Typically, the magnetic head is attached to a positioner arm assembly that uses a motor to align the magnetic head above a selected track on the disc. The location of the magnetic head is typically determined by a disc controller that is given the position of a data area on the disc to read or write data. The precise location and movement of the head is typically accomplished by incorporating a closed-loop electro-mechanical servo system with a dedicated servo region, or regions, used to provide high speed or continuous feedback to the system to maintain accurate positioning of the data head.
Due to their large storage capacity relative to other forms of electronic digital data storage, disc drives are often used by electronic systems such as computers to permanently or semi-permanently store applications, e.g., image files, software programs, data, etc. The amount of data stored on disc drives is a function of the media density, size, and number of medias used. The applications are generally stored as files that are then used by an end user, or users, to perform tasks such as word processing, calculations, and the like. To assist the applications in locating a file, conventional computer operating systems generally use a layered directory structure. The conventional layered directory structures usually have a main directory and then sub directories where the files are stored. For example, using the DOS operating system, a file named “xyz” may be given a logical location such as “c:/xyz” indicating that the file is located on the “c” drive at the root directory “/”.
To allow an application to find and use files on the media, each file is given a different logical location on the media by the computer operating system. Operating systems communicate with the disc drive using logical block addresses (LBA). When an application makes a request for a file from the operating system, the operating system uses the file name to look up the location in terms of a starting LBA and the number of LBAs needed to read or write the file. The LBA is then translated by internal disc drive software to the actual physical location on the disc drive, i.e., the physical block address (PBA). The PBA includes a number of data sectors depending upon the location of the PBA on the media for storing data. The translation from LBA to PBA is necessary to allow the disc drive to implement a defect management scheme and to set aside reserved areas on the media for manufacturer specific data not generally accessible to the operating system such as disc drive operating firmware, etc.
Currently, with limited data storage available to peripheral devices, the disc drive is becoming a preferred storage medium for large files such as a digital image files. Unfortunately, peripheral devices such as printers do not have operating systems that interface directly with disc drives. Generally, to transfer a file from a disc drive to a printer requires the user to use a computer having the proper device driver(s) to establish the interface and transfer the files. While some peripheral devices such as digital cameras may directly connect to printers having the proper communication interface such as a universal serial interface (USB), those devices having 1394 interface and/or an infrared data association (IRDA) wireless connection must also rely on a computer to handle the data transfer. Although the some disc drives may interface with a computer directly through the USB, the required data structure and printer drivers are not available to the disc drive except when working in conjunction with a computer operating system.
Thus, what is needed is a method and apparatus that allows the disc drive to interface and transfer data directly to a host device such as a printer in an efficient and effective manner.